Author Archive | Deidre Sullivan

Students in the Marine Science Technology Program (MST) have recently built and deployed an ocean drifter designed to study California coastal currents. The drifter is a four-and-one-half foot tall by four foot wide structure made of PVC pipe, vinyl “sails” and a package containing a satellite transmitter. The drifter is designed to float just below the surface of the ocean so that its path is largely unaffected by the wind. A satellite tracking device protrudes above the ocean surface so the path of the drifter can be monitored by MST students, scientists and the public.

It was dropped into the Pacific Ocean on Tuesday May 11 with the help of the F/V Trek II about two miles offshore of Noyo Bay. The students have been waiting for ideal oceanographic conditions to drop the drifter to utilize the dominate California Current that flows from north to south, fueled by a northwest wind pattern. Strong northerly winds also foster coastal upwelling that pushes surface waters offshore. Upwelling brings cold, nutrient-rich waters to the surface and sustains the tremendously diverse coastal ecosystem along the Mendocino Coast. Information gathered by the drifter will be used in future MST Program classes, such as the Oceanography class that will be offered this coming fall semester. Even if ocean currents force it up on the beach, the drifter can be recovered and redeployed unless it is too damaged.

Funding and support for the project came from the Marine Advanced Technology Education (MATE) program in Monterey via a grant from the National Science Foundation. Scientists from Woods Hole Oceanographic Institute in Massachusetts provided materials and technical support to assist CR students to assemble the drifter, and the federal National Oceanographic and Atmospheric Administration (NOAA) has donated the satellite time to track the drifter.

Except from Podcast: Kara La Lomia is part of a team at Southern Maine Community College (SMCC) that’s designing, constructing and using drifters. These floating instruments track the currents, and are engaging everyone from students to lobstermen. To listen go to http://coseenow.net/podcast/2010/02/drifter/

In an effort to plug gaps in knowledge about key ocean processes, the National Science Foundation (NSF)’s division of ocean sciences has awarded nearly $1 million to scientists at the Scripps Institution of Oceanography in La Jolla, Calif. The Scripps marine scientists will develop a new breed of ocean-probing instruments. Jules Jaffe and Peter Franks will spearhead an effort to design and deploy autonomous underwater explorers, or AUEs. AUEs will trace the fine details of oceanographic processes vital to tiny marine inhabitants.

While oceanographers have been skilled in detailing large-scale ocean processes, a need has emerged to zero in on functions unfolding at smaller scales. By defining localized currents, temperature, salinity, pressure and biological properties, AUEs will offer new and valuable information about a range of ocean phenomena.

“We’re seeing great success in the global use of ocean profiling floats to document large-scale circulation patterns and other physical and chemical attributes of the deep and open seas,” said Phillip Taylor of NSF’s division of ocean sciences. “These innovative AUEs will allow researchers to sample the environments of coastal regions as well, and to better understand how small organisms operate in the complex surroundings of the oceans.”

For marine protected areas, AUEs will help inform debates about the best areas for habitat protection. With harmful algal blooms and oil spills, the instruments can be deployed directly into outbreak patches to gauge how they develop and change over time. In the case of an airplane crash over the ocean, AUEs should be able to track currents to determine where among the wreckage a black box may be located.

“AUEs will fill in gaps between existing marine technologies,” said Jaffe. “They will provide a whole new kind of information.”

AUEs work through a system in which several soccer-ball-sized explorers are deployed with many tens–or even hundreds–of pint-sized explorers. Collectively, the entire “swarm” of AUEs will track ocean currents that organisms at a small-scale, such as tiny abalone larvae, for example, experience in the ocean.

“AUEs will give us information to figure out how small organisms survive, how they move in the ocean, and the physical dynamics they experience as they get around,” said Franks. “AUEs should improve ocean models and allow us to do a better job of following ‘the weather and climate of the ocean,’ as well as help us understand things like carbon fluxes.”

Franks, who conducts research on marine phytoplankton, says that “plankton are somewhat like the balloons of the ocean floating around out there. With AUEs, we’re trying to figure out how the ocean works at scales that matter to plankton.

“If we place 100 AUEs in the ocean and let them go, we’ll be able to look at how they move to get a sense of the physics driving current flows.”

During the pilot phase of the project, Jaffe and colleagues will build five to six of the soccer-ball-sized explorers and 20 of the smaller versions. An outreach component of the project will enlist school children in building and ultimately deploying AUEs.

In a related funding award, the researchers have also been given $1.5 million from NSF’s Cyber-Enabled Discovery and Innovation initiative to design and develop the systems necessary to control the movement of AUEs.

That aspect brings Jaffe and Franks together with researchers at the Cymer Center for Control Systems and Dynamics at the University of California at San Diego’s Jacobs School of Engineering and the San Diego Supercomputer Center.

A couple of MPC Oceanography students accompanied the MBARI team to recover the drifters yesterday. They quickly found both of them and brought them back on board. They were out for almost exactly 48 hours. After drifting south for the first 12 hours or so, perhaps due to strong NW winds that day, they turned and drifted north and west, along the expected counterclockwise rotation of surface water in Monterey Bay.

Here is a quick and dirty cut and paste job of their complete paths. I don’t have the software set up yet to make my own maps of their paths. These are from the AeroStar tracking website. They generally drifted from southeast to northwest.

We’re very happy with this first deployment of the drifters and thank the MBARI team of John Ryan and Erick Rienecker. The MPC students seemed to enjoy it as well. Four of the five we sent came back very enthused about the whole experience. They took some pictures, but I haven’t been able to get their pics downloaded onto my computer. Maybe we’ll see some next week.

So I’m thinking about how to integrate this stuff into my lesson plans for next week. I’m thinking of creating a short activity where we ask the question, “Did the tsunami affect the movement of the drifters?” This will involve the following aspects of data manipulation:

Determining the time the Tsunami hit Monterey

Making a hypothesis about whether or not the tsunami affected the drift

Identifying exactly what we would see, and on what timescale, if the tsunami affected motion.

Manipulating the Aerostar tracking site to find times and positions of data points

Looking at the data to determine if the identified changes in motion did or did not take place.

The anticipated outcome is that the tsunami did not, in fact, influence the movement of the drifters. Hopefully, this will be a useful realization that wave motion and current motion can be totally different because they are totally different processes. We know, for example, in the northeastern part of Monterey Bay that the longshore drift of the sand on the beaches is in exactly the opposite direction (west and southwest towards Moss Landing) than the surface currents (north and west, as our drifters demonstrated). So it would follow that tsunami motion would not necessarily be detected, especially at the temporal resolution available to the drifters (one measurement every half hour).

This is what the path of one of the drifters looks like today, approximately 24 hours after deployment. Remember yesterday, the drifter was taking a southerly route. Today, the drifters have turned northwards. Today is not as windy as yesterday.

This is what the other drifter path looks like today. It has also turned north after drifting south the first day. This one may have drifted further south the first day because it was deployed closer to the Salinas Valley, where the onshore winds are strongest. Well, maybe.

Here’s what the winds look like today. You can definitely see that the wind speeds are lower today, especially in the northeast portion of the bay where the drifters were deployed.

We had a bit of a distraction today with the Samoan earthquake and tsunami. The tsunami made it all the way to Monterey by yesterday evening, although its amplitude was only a few centimeters by the time it made it here.

In the image above (click on it for a larger image), you can see that the tsunami entered Monterey Bay at just past 0400 on Day 273, which is Sept 30, 2009. I guess we can say that the drifters survived a tsunami on their maiden voyage.

I just got word from the MBARI guys that the drifters will be recovered tomorrow. We’ll be sending a few more students on the cruise with them.